1. Field of the Invention
The invention generally relates to a containment housing having an alternate inlet field and a method for leak testing a filter installed in the containment housing have an alternate inlet field. The invention also relates to an air distribution plate.
2. Description of the Related Art
FIG. 1 depicts a conventional containment system 100 having an inlet 124 and an outlet 126. The conventional containment system typically consists of multiple components arranged in series in a containment housing 102. The components in the containment housing 102 generally include one or more pre-filters 104, a main filter 106, a scanning mechanism 108, an upstream section 110, and a downstream test section 112. The containment system 100 also includes a pre-filter access door 116, and a main filter access door 118. The filter access doors 116, 118 may be opened to replace the respective filters 104, 106 disposed in the housing 102 and closed to sealingly isolate the interior of the housing 102 from the surrounding environment.
Isolation dampers 114 are located upstream and downstream of the containment housing 102 and the test sections 110, 112. The dampers 114 allow the containment system 100 to be sealed air-tight during system decontamination. Transitions 120 are disposed between the isolation dampers 114 and the other components of the containment system 100 to improve airflow. The dampers 114 may be bolted or welded to the transitions 120. Additional ductwork 122 may be disposed between the dampers 114 and the transitions 120.
The upstream section 110 is for the introduction of an aerosol challenge upstream of the filter components 104, 106 and for the measurement of upstream challenge concentration. Conventional upstream sections typically include baffles to achieve adequate aerosol mixing such that testing may be performed to ANSI, IEST or other standard. In addition to the pre-filter 104, the containment housing 102 may hold one or more intermediate filters, HEPA filters, HEGA filters and/or other filtration components required for the specific application. It is contemplated that the main filter 106 may be a panel filter, v-bank filter or other type of filter configuration.
The downstream test section 112 is used to conduct scan testing and validation of the HEPA filter(s) to determine the location and size of any leaks in the filter(s). A bag with gloves (not shown) is generally coupled to an access door flange (not shown) of the downstream test section and utilized to position the scanning mechanism 108 during testing of a filter disposed in the containment housing 102.
This configuration for a conventional containment system is very large, typically in the range of about 130 inches in length, and requires significant space and cost for installation. Often times the size of the conventional containment system does not allow for alternate inlets and outlets which could be utilized for testing filters installed in the containment system to be incorporated into the design of the containment system. Therefore, in addition to the containment system, all wetted areas, including laboratory and upstream and downstream ductwork must be taken offline and completely decontaminated prior to introducing an aerosol challenge. As containment systems are relied upon in labs testing the most toxic and virulent chemicals, agents, viruses and organisms, the down time associated with taking the containment system offline is extremely costly. Thus, there is a need for an improved containment system that has alternate inlets and outlets to more efficiently test the filters in the containment system.